The present invention relates to a method for manufacturing welded foam panels. More specifically, the invention relates to a method for linearly welding a thermoplastic material to a permeable foam material.
It is desirable to use foam materials to provide bulk and crush features to automobiles. Rigid foams have been found to be especially useful in absorbing energy in the event of a collision. Rigid foams have been successfully used as bolsters in the interior of an automobile. Attaching rigid foams to plastic components has generally required the use of adhesives or mechanical fasteners.
U.S. Pat. No. 4,770,730 teaches ultrasonically welding a soft elastomeric foam to a thermoplastic covering. Both the foam and the covering are heated through ultrasonic vertical vibrations until both the foam and covering soften and weld together. U.S. Pat. No. 5,026,445 teaches vibration welding carpeted panels. The patent teaches that carpets made with a thermoplastic material soften and flow in response to frictional heat. The materials will adhere to one another and bond.
U.S. Pat. No. 5,076,870 teaches vibration welding heat fusible nonwoven backing material to a vehicle door trim. This patent teaches fusing the nonwoven material to a fusible panel.
Vibrational welding had generally been limited to welding two similar or compatible materials to the point of softening so that they weld together and bond. Rigid foam materials useful as bolsters generally do not soften under welding.